An effort will be made to investigate the effects of extracorporeal circulation on the formed blood elements. Prolonged perfusion, both in vivo and in vitro, is known to produce "toxicity" of blood. Morphological and biochemical parameters will be investigated using a pump alone, the pump plus an oxygenator, and the pump-oxygenator with a patient or animal. Normal individuals, normal animals, and patients and animals undergoing other major surgical procedures will serve as controls. The following will be determined: Erythrocyte morphology and metabolism, particularly those related to lipids and membrane transport; platelet counts and morphology; platelet survivals; platelet and serum content of adenosine triphosphate, adenosine diphosphate and adenosine monophosphate; platelet adhesiveness; platelet ADP; platelet aggulatination; platelet and erythocyte alkaline phosphatase; serum and platelet lipid contents; platelet proteins; platelet and erythocyte cathepsin, catalase, lactic dehydrogenase, glucose-6-phosphate and 6- phosphogluconic dehydrogenase; erythrocyte destruction rate (by isotope or CO production techniques); bone marrow biopsy and cultures; leukopoietin bioassay; platelet antibodies. Biochemical studies of plasma protein alterations associated with pumping and oxygenation will also be undertaken.